Olefin treatment by solvent extraction

ABSTRACT

OLEFINS, SUCH AS C5 TO C30 ALPHA OLEFINS FORMED BY THERMAL CRACKING OF LONG CHAIN NORAML PARAFFINS, ARE SUBJECTED TO SOLVENT EXTRACTION TREATMENT BY CONTACTING THE OLEFINS IN LIQUID PHASE AT A TEMPERATURE OF ABOUT 50* TO BOUT 350*F., PREFERABLY, FORM ABOUT 65* TO BOUT 275*F., WITH AN ALKYLENE GLYCOL OR CYCLOALKYLENE GLYCOL SUCH AS ETHYLENE GLYCOL, 1,2-CYCLOHEXYLENE GLYCOL, ETC. THE THUS-TREATED ALPHA OLEFINS WHICH ARE LOW IN CONJUGATED POLYENES, I.E., DIENES, ARE HIGHLY USEFUL FOR PRODUCTION OF OLEFIN SULFONATE DETERGENTS HAVING AN IMPROVED COLOR.

United States Patent 3 803 257 OLEFIN TREATMENTBYSOLVENT EXTRACTION William J. Powers III and Anthony Macaluso, Sn, Port Arthur, Tex., assignors to Texaco Inc., New York, NY. N0 Drawing. Filed June 14, 1973, Ser. No. 370,193 Int. Cl. C07c 7/00 US. Cl. 260-677 A 12 Claims ABSTRACT OF THE DISCLOSURE Olefins, such as C to C alpha olefins formed by thermal cracking of long chain normal paraflins, are sub jected to solvent extraction treatment by contacting the olefins in liquid phase at a temperature of about 50 to about 350 F., preferably, from about 65 to about 275 F., with an alkylene glycol or cycloalkylene glycol such as ethylene glycol, 1,2-cyclohexylene glycol, etc. The thus-treated alpha olefins which are low in conjugated polyenes, i.e., dienes, are highly useful for production of olefin sulfonate detergents having an improved color.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to an improved process for the purification of olefins. More particularly, this invention relates to a process in which liquid olefins, such as alpha olefins of C to C carbon chain length are treated by contacting the olefins with an alkylene or cycloalkylene gly-- col such as propylene glycol or 1,2-cycloheptylene glycol. Such treated olefins are useful for preparing olefins sulfonates of improved color.

Description of the prior art Thermal cracking of long chain normal parafiins is the form highly colored compounds onreaction with S0 .v

These intensely colored compounds which are present in the sulfonate product are likely polysulfonated polyenes which possibly are derived by polymerization and subsequent sulfonation.

When commercial alpha olefins are utilized in preparing olefin sulfonates for use in detergent compositions it is necessary to treat the olefin employed prior to sulfonation in order to reduce the color level of the sulfonate product. A variety of processes have been advanced in the art for accomplishing this, however, they all suffer from one or more serious disadvantage. It has been suggested that the olefins be purified by passing them over adsorbents, such as clays, or that they be washed with a variety of solvents. Likewise, treatment of the olefins with sulfuric acid followed by water washing has been employed however, because of the numerous processing steps (i.e., contacting the olefin with the acid, allowing 3,803,257 Patented Apr. 9, 1974 the mixture to settle and removing the acid layer, neutralizing the olefin layer followed by repeated washing and finally drying), because the treatment has often resulted in the isomerization of some of the olefins to internal olefins, and because the olefins react to some extent with the sulfuric acid itself, this process has not proven to be satisfactory in practice.

Acid treatment of the cracked wax olefin feed, according to the process of US. 3,492,343, prior to sulfonation, results in the removal of the color precursors, i.e., the conjugated diand polyenes from the olefin feed stream, and in the production of an AOS product with acceptable color properties. In this process, the olefin feedstock is contacted with aqueous sulfuric acid, the aqueous and organic layers are separated and the latter is contacted with an adsorbent such as fullers earth. The process, as described, suffers from several disadvantages in commerical operation:

'(1) The treating agent, 85 to 87 weight percent sulfuric acid, is highly corrosive to standard metallurgical systems,

(2) The acid concentration and contacting and settling timesare highly critical, and

3) The process is less effective from the point of final AOS color when operated continuously than when it is operated batchwise.

There is a definite need in the art, therefore, for an efllcient process for treating olefins so that they are suitable for the production of detergent grade sulfonates. A principal object of this invention is to provide an cfiicient treatment process for the removal of color precursors such as conjugated polyenes (i.e., dienes) from olefin streams such as those derived by wax cracking.

BRIEF DESCRIPTION OF THE INVENTION In the process of this invention olefins having from 5 to 30 carbon atoms and, preferably, alpha olefins of the formula: I Y

RCH=CH,

wherein R is straight chain alkyl of from 3 to 28 inclusive carbon atoms, as exemplified by propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, pentadecyl, nonadecyl, eicosyl, hexacosyl, heptacosyl, etc. are subjected to solvent extraction treatment by contacting the olefin in liquid phase with an alkylene or cycloalkylene glycol at a temperature of about 50 to about 350 F. and, preferably, at about to about 275 -F. Mixtures of the abovedescribed alpha olefins, such as C -C alpha olefins, Cir-C12 alpha olefins and G -C alpha olefins, may be advantageously employed as feed stocks for the olefin purification process of this invention.

'It has been found that the process of this invention in which the olefins are purified by contacting them directly with an alkylene or cycloalkylene glycol, possesses a number of significant advantages over other art recognized processes, namely:

(1) Noncorrosive extractants are employed,

(2) The process may be conducted over a wide range of operating conditions,

(3) Polyenes present in the olefin feed are removed from the process in a stream concentrated in polyene content, and

(4) There is no net consumption of the purifying or extracting agent since the extraction agent can be conveniently recovered and recycled to the process.

INVENTION Damian DESCRIPTION OF THE olefins are purified by treatment or contact with a selective solvent in which the conjugated dienes in the raw olefin stream dissolve. The resulting solvent layer which forms is separated from the raffinate layer by decantation, centrifugation, or by any other convenient method to yield a purified olefin product of substantially lowered conjugated dienes content. The contacting of the alkylene or cycloalkylene' glycol with the olefin feed may be accomplished by admixing the solvent with the olefin in a variety of ways either in batch or on a continuousbasis. For example, the solvent may be admixed with the-olefin feed in an agitatd,-bafiied tan-k equipped with a bottom draw-off to permit removal and separation of the solvent (layer) from the rafilnate layer at the conclusion of the mixing cycler' I'hesolvent can be commingled with the olefin --in a pipe or turbulent reactor after which the treated mixture is sent to adecanter or some otherape propriate device to permit separation of the. resulting two phases. If desired, the solvent treatment can be carried out in stages. The purification of the olefin stream can also be conducted using a rotating disc contactor or under countercurrent extraction conditions where the olefin stream to be purified is passed in a eountercurrent manner through a downward flowing stream of the solvent with the purified olefin stream being withdrawn from the top of the extraction vessel'and the solvent phase conraining a substantial proportion ofthe conjugated polyble of dissolving the conjugated polyenes vw'thout reacting with the olefin itself. Preferred solvents include those glycols having the formula:

wherein R is alkylene of from 2 to about 16 carbon atoms, and cycloalkylene glycols of the formula:

wherein n is an integer of item 2 to about 14. Especially useful alkylene glycol solvents include ethylene glycol, 1,2-propylene glycol, 1,3-propylenev glycol, 1,2-butylene glycol, 2,3-butylene glycol, 3,4-pentylene glycol, 1,2-hexylene glycol, 3,4-heptylene glycol, 3,4hexylene glycol, 3, 4 -octylene glycol, 1,2-pentylene glycol, 1,2-nonene glycol, etc. and cycloalkylene glycols as exemplified by 1,2-cyclopentene glycol, l,2-cyclohexene glycol, 1,2-cycloheptene glycol, and 1,2-cyclodecene glycol, etc.

The amount of the inert alkylene or cycloalkylene glycol solvent employed may be varied over a wide range, however, it should be suflicient'to dissolve the desired amount of the conjugated polyenes from the olefin stream The actual amount utilized will depend on theparticular solvent selected, the degree of solubility of the conjugated polyene in the solvent, the temperature at which the process is conducted, the efficiency of contacting, etc. Generally, the total amount of solvent employed will be from about to about 250 weight percent based on the weight of the olefins charged. The pressure under which this process is accomplished may likewise be varied from subatmospheric to atmospheric to superatmospheric. Atmospheric pressure operation is preferred. Generally, the pressure employed will be from about 0 to about 100 p.s.i.g. although the pressure used should be sufiicient to maintain the olefin stream and the solvent in the liquid state.

The following examples illustrate various embodiments of this invention and are not to be considered as limitative.

EXAMPLES I AND In these examples the olefin and propylene glycol solvent were charged to a 2,000 ml. flask equipped with a bottom draw-oft following which the charged liquids were stirred briskly for 10 minutes. The solvent (lower) layer was then withdrawn and the solvent for the second stage of the extraction was added, stirred and withdrawn. The third stage of the extraction was similarly performed. In the next step, the raflinate was washed with grams of water and analyzed for conjugated diene content by ultraviolet spectroscopy. The ,combined'extracts were stirred with 400 grams of water to dissolve the solvent and spring the conjugated diene concentrate. Pertinent details relating to these examples are set forth in Table I which follows. As shown in Table I in these two'exarnples a high percentage of the conjugated dienes initially present inthe olefins charged was removed by the process of this invention. The thus-treated olefin fractions are highly suitable for the preparation of olefin sulfonate detergents of reduced color level.

TABLE I.SEPARATION OF CONJUGATED DIENES FROM CRACKED WAX OLEFINS BY EXTRACTION WITH PRO- PYLENE GLYCOL Examplenumber I 11 Charge wt., grams Conjugated diene content, chg. mol. percent 1. 07 Wt, propylene glycol/stage, grams. 50 Number of stages 3 Wt. of rafiinate, grams 44 47 Conjugated diene content, raflinata moi. percent. 0. 63 O. 79 Percent conjugated diene removal 41. I 24. 4 Wt. of water sprung extracts, grams 2 Conjugated diene content, extract, mol percent 2. 5 2. 7 Wt. percent recovery 96. 0 98. 0

I Clo-C1D olefin traction charged (predominantly alpha olefins), ex-

. traction at 250 F.

We claim: i

1. A process for treating an alpha olefin having from 5 to 30 carbon atoms to remove conjugated polyenes therefrom which comprises contacting the said olefin in liquid phase with a solvent selected from the group consisting of alkylene and cycloalkylene glycols whereby a liquid olefin phase and a solvent phase having dissolved therein a substantialproportion of the conjugated dienes are formed and separating the olefin phase from the solvent phase.

2. The process of claim 1 wherein the said alkylene glycol has the formula:

wherein R is alkylene of from 2 to about 16 carbon atoms and the said cycloalkylene glycol has the formula:

wherein n is an integer of from 2 to about 14.

3. The process of claim 1 wherein the said olefin is a mixture of C -C alpha olefins.

4. The process of claim 1 wherein the said olefin is a mixture of 0 -0 alpha olefins.

5. The process of claim 1 wherein the said olefin is a mixture of C -C alpha olefins.

6. The process of claim 1 wherein the said olefin is contacted with the said solvent at a temperature of about 50 to about 350 F.

7. The process of claim 1 wherein the said solvent is an alkylene glycol.

8. The process of claim 1 wherein the said solvent is propylene glycol.

9. The process of claim 1 wherein the said solvent is 2,3-butylene glycol.

10. The process of claim 1 wherein the said solvent is a cycloalkylene glycol.

11. The process of claim 1 wherein the said solvent is 1,2-cyclohexylene glycol.

5 6 12. The method of claim 1 wherein the said olefin is a 3,094,571 6/1963 Wilson, Jr. et a1. 260-677 A mixture of 0 -0 alpha olefins and the said solvent is 3,201,492 8/1965 Sherk 260-6815 R propylene glycol.

References Cited DELBERT E. GANTZ, Primary Examiner UNITED STATES PATENTS 5 J. M. NELSON, Assistant Examiner 2,925,452 2/1960 Broughton 260-677 A US. C1.X.R.

2,834,820 5/1958 Bloch 260-677 260-6815 

